A MEMS pressure sensor is known as one of the devices utilizing MEMS elements. The MEMS pressure sensor comprises a substrate, a fixed electrode (lower electrode), a movable electrode (upper electrode) and a diaphragm (domed thin film). The fixed electrode is formed on the substrate. The movable electrode is formed on the inner upper surface of the diaphragm.
When the diaphragm is sagged by pressure, the distance between the fixed and movable electrodes varies, thereby varying the electrostatic capacitance therebetween. The MEMS pressure sensor employs a principle that pressure is detected utilizing the relationship between pressure and electrostatic capacitance. There is a demand for high detection accuracy.